This invention relates to a process for deriving a measuring signal dependent on the temperature rise of a temperature-time characteristic curve of a heating system comprising a cooker with cooking materials on a heating plate, and in which, by means of a temperature sensor, the temperature in or on the cooker is measured.
In such a heating system, the measuring signal may be converted into a control signal and used to regulate the thermal output of the heater, since thermal output must be increased or reduced according to the temperature change, considering various time constants of the heating system, to avoid exceeding the desired temperature after reaching the cooking temperature, which can then be held constant by means of a regulating circuit.
The analogous determination and evaluation of the temperature rise requires complex switching circuits. If the evaluation is computed digitally, then, because of the turbulent disturbances arising during the final phase of the heating process, brief temperature oscillations occur, which can lead to considerable inaccuracies in measurement, which may be further increased, if the digitally determined temperature increments, based on a lesser circuit complexity, are relatively great. These temperature oscillations which are caused by turbulent disturbances in the cooker appear especially when the temperature at which the steam phase begins, that is, around 90.degree. C., is reached in the cooker.
Since the transition from this temperature to the regulated cooking temperature is very strongly dependent on the quantity of cooking material in the cooker, it is especially important to precisely determine the temperature rise during the final phase of the heating process.